Identification and characterization of sexual dimorphism-linked gene expression profile in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is sexually disparate in humans, with a significantly increased prevalence in males. The molecular mechanisms by which the inhibition or development of liver cancer are facilitated require further investigation with regard to sex factors affecting disease progression. In the present study, functional signatures of differentially expressed genes (DEGs) were screened in female and male tumors via bioinformatics analysis. The following gene chip expression profiles were downloaded from the Gene Expression Omnibus: GSE19665, GSE23342 and GSE9843. They comprised cancerous and non-cancerous tissue from patients with HCC and included critical sex features. Further evaluation of selected DEGs in the two sexual groups was performed via hierarchical clustering analysis. Venn diagram and functional protein-protein interaction (PPI) network analyses were performed. Survival analysis of patients with differences in gene expression levels was subsequently performed using the Kaplan-Meier Plotter database. Certain identified DEGs were common in female and male tumor samples, whereas others exhibited a sexually-biased expression profile. Gene Ontology revealed that the cell cycle module ‘biological process’ was enriched in tumors derived from both sexes, whereas the metabolic pathways and drug metabolism modules were only significantly enriched in cancer tissues from male subjects. A number of hub DEGs in the cell cycle and p53 signaling pathways were involved in significant protein-protein interaction (PPI) modules, including CDK1 and CCNB1. These DEGs were upregulated in tumors derived from female subjects compared with those derived from male subjects, and could be used as markers of poor prognosis in male patients. Other genes, such as CYP3A4 and SERPINA4, were identified in metabolic pathways, and were downregulated in male compared with female subjects. These genes were associated with a decreased survival rate. The data demonstrated that sex differences in physiology may regulate the levels of gene expression and/or activity, including gene function associated with oncogenesis and the outcomes of liver cancer. Additional surveys are required to explore in detail the molecular mechanisms underlying the differences in gene expression between the two sexes during the development of liver cancer.